Gas turbines are widely utilized in fields such as power generation. A conventional gas turbine system includes a compressor, which compresses ambient air; a combustor for mixing compressed air with fuel and combusting the mixture; and a turbine, which is driven by the combustion mixture to produce power and exhaust gas.
Various strategies are known in the art for increasing the amount of power that a gas turbine is able to produce. One way of increasing the power output of a gas turbine is by cooling the ambient air before compressing it in the compressor. Cooling causes the air to have a higher density, thereby creating a higher mass flow rate into the compressor. The higher mass flow rate of air into the compressor allows more air to be compressed, allowing the gas turbine to produce more power. Additionally, cooling the ambient air generally increases the efficiency of the gas turbine.
Various systems and methods are utilized to cool the ambient air entering a gas turbine. For example, heat exchangers may be utilized to cool the ambient air through latent cooling or through sensible cooling. Many such heat exchangers utilize a media pad to facilitate cooling of the ambient air. These media pads allow heat and/or mass transfer between the ambient air and a coolant. The ambient air interacts with the coolant in the media pad, cooling the ambient air.
Known media pads for use in heat exchangers are formed from, for example, cellulose fibers. Cellulose fiber-based media pads generally include a stiffening agent designed to maintain the structural integrity of the media pad when a coolant, such as water, is flowed through the media pad. However, cellulose fiber-based media pads are generally not suitable in situations requiring a high volume of coolant, which may dissolve the stiffening agent and collapse the media pad. Further, cellulose fiber-based media pads may be particularly sensitive to the quality of coolant flowed therethrough, and may therefore require the use of “fouled” coolant rather than clean coolant for the media pad to perform properly.
Other known media pads are formed from non-porous, solid plastic materials. These media pads are generally not able to evenly and fully distribute coolant throughout the surface area of the pads. This can inhibit efficient cooling of the ambient air and, in some cases, may result in dry spots that cause hot streaks of air, which can be detrimental to the operation of the gas turbine compressor. Additionally, at relatively higher air flow velocities, these media pads may be unable to retain the coolant, and may instead have a tendency to shed coolant.
Thus, a media pad that provides more efficient cooling and is not sensitive to coolant quality would be desired in the art. Additionally, a media pad that will maintain structural integrity when a high volume of coolant is flowed therethrough would be advantageous. Further, a media pad that reduces or prevents dry spots and resulting hot streaks would be desired. Finally, a media pad that retains coolant at relatively higher air flow velocities would be advantageous.